Ammeter



Nov. 19, 1929.

J. E. ESHBAUGH AMMETER Filed sept. 22, v192'/ gwwmtoc V gif/55e 5. waag@ Patented Nov. 19, 1929 Jnssn E. ESHBAUGH, or FLINT, MICHIGAN, Assienon-fro A osrAR-K PLUG CQMPANY, or FLINT, iiiicnicfiiiv, a COMPANY or ivrrcniieraitl i, AMMETER l y applic-ation mea september 22,1927. lseiiai No. 221,313. 4 Y

Y This inyention relates tov ammeters and particularly to ammeters offthe type ordinarily mounted on the dashboard of an automotive vehicle. t Y Y Ammeters of this type ordinarily include v La section of a conductor through which the current to be measured passes, a pivotally mounted armature carrying an indicating needle, a dial, and a permanent magnet placedto hold the armature parallel With a section of the conductor. y A diliculty encountered Withfsuch a structure is that as ra current passes through the conductor, the

armature is` moved romva position perpen dicular to a tangent. tothe lines of force Y divisions on the scale must increase from Zero in either direction. v, t It is an objectl of this invention'to remove VVas far as possible the highly congested scale which is generally characteristic of an ammeter of thisclass and to secure a certain amount of pointer dampingt v Y AI vaccomplishthis result by so shaping the conductor that as the armature rotates it moves into Za magnetic eld of progressively increasing intensity per unit of current.

Other objects of the invention will appear in the course of the lfollowing description,

.taken in connectionyvith the accompanying drawing and appended' claims.

'Figure 3. Y l Y. A

' Figurel 5 is a vertical longitudinal section Y of the device.

Inthedravving:` y

Figure 1 is a vertical longitudinal section 'Figure 2 is a section on the line ,i2-270i 'Figure 1, With parts brokenavvay.) f A Figure 3 is a section on the1line3-3fof Figurepl. y Y

Figure 4 is a section on the line 4 4 of of a inodiedyfor-m of my invention.'

' FigureY 6 is asection `on tlieline-G of Figure 5f the casing. 'y

Figure 7 is adiagrammatic vie'vv taken in a vertical transverseplane and illustrating permanent magnet and the conductor. y

Figure 8 is a separated view of thecon-` vthe direction of the lines ofpforce from the nection between the pointer, shaft and armature.

Referring to the drawing the numeral 10 indicates the usual cup-shaped case, flanged atvits rim and provided in its/rear face with apertures for the reception of the terminal bolts.' Fixed to the rear faceof the case is the conductor :trame 11 through Which passes the current to bemeasured. ln `the embodi-l `ment:illustrated in Figures 1 to 4, the con-` ductor trame 11 Vcomprises tWo similar oppo? and a central bridge member 14, the parts `being lifted together by bent dovv'n lportions or lugs 16 on central member "14.:Eache .bracket or side member 12 has oney end bent at right angles to form a toot' 13 which is provided With an up-turiied end 18 for fitting lsitely disposed brackets or side members *12T Y against thestraight side of the head 2O of the terminal bolt 21. rlhel opposite ends V17, of

the brackets 12 areV flanged orturned away from the main or central portion thereofto form ai seat for the bridge member 14.-v The A.

'ends of the-flanged portions 17 are in Vturn bent as at 19. The side member 12 heldv by the terminal bolt 21 against the rear face of the Ycasel by means of theiiut 26'. The -rame I11 is 4spaced from thev casing-'by a -strip .22 of insulating material, vand .an' insulating .QWasher24 is placed between the nut 26'and Thevnnr; adjacent vportions of vthe side i members `1 2'have WallsBO which are arcuate in shape. ',The arcuate fWalls :80 foi? the brackets 12 are preferably ythoughiot necessarily portions of the same cylindrical;sur-f face asis seen Figures 2, 3, and."` The central bridge member 14 is. provided With 'a i bridge(` 14. The opposed faces lof the' end of' the bridge 14 are prick punched to provideA Y g' an 'armature olfV magnetic metal., "The arr-j` 'Y rearwardly bent 'portion 32, theend' 330i' i' Which 'extends under themi'dV-portion of the.

v bearings forthe cone-shapedl ends 31 of the shaft-34on Which is mounted aneedle 38and Y mature is mounted'on the shaft by means of parallel slits or openings and 37 as illustrated, the tension ofthe metal holding it iii kpositionwithout other lfasteningV means. As

`shown in Figures l and'8, the needle extends around the'sliaftand has a portion 39wliich extends downwardlyy and ythen Arearwardly and is held between the shaft and a portion.

kof the armature. This arrangement proposition.

vides means for quickly Aassembling the needle'and armature on the shaft,the tension of the metallic armature being suicientgto insure that the parts will be heldl firmly in This arrangement avoids the .Y necessity of using collars, bushings or wax to "hold the- "needle Yand armature on the shaft. The-shaft onfwliicli the armature and needle areiiiountedis centrallydisposed with rela# tion to tlie-arcuate portions- 30 of the side :members 412.' j v `Fitting-'against"the conductor -frame and V`held against movement relative theretoby l ,'mean'so'f bent up 'gportionsor lugs 4L() of Athe bridge M 'of thecoonductor frame isy the peri manen-t magnet. Extending overv the magnet is the: dialtli.' The dial, magnet and con- V` Y `ductorl'frame lare lieldtogether by rivets 46.

The dialis' providedwitli an arcuate slot-48 throughlwli-ich passestlie offsetportion i9 of the indicating needle l38.- 'The usual glass f cover 50 and bezel 52* are'providedfor making Ythe case dustproof.

In the modification sliownin Figures 5 and Gthe' conductor frame "llf isI formed of a 'jfsingle slieet'ofnietal, pressed into the shape Y described above. Theframe 1l i-nthis species comprises the cup -shfaped central portion'liavingtthe'bottonilt and thearcuatesides 30',

and the flanged extensions 17. The cup bottom flt" lhas the linger 60, which is Vpreferably integral, bent to have its "end 33 extend under ther'central'ormidportioii of the cup bottom "14C The magnet @and dial laj'aremounted foiithe bottom 14;',` inany suitable way. lVith theseexceptions, Vthe structure ofjthis modi- `fication is the same asthat ofthe embodiment disclosed in Figuresl1 tov 4,' except for slight changeslindimensions. Y

in Figure .7- i ,have-nirwana@ diagrammatically the magneticfieldlwitli'a currentf passingthrough the conductor. f vrThe lines j of 'the' permanent magnet extend from centric with. said sections, and a the edges, the lmagnetic field about the curved walls 30 or a given current passing there-V througliis lessiiitense at the centerthan at the adjacent edges of the arcuate portions. This is. illustrated by the wider spacing of the where the distance between the two curved sections-.of lthe conductor-is lessandhence the component magnetic flu-X per unit of area is greater. `This factor `compensates for the normal lessening of the ydeflection ordinarily occurring as the armaturek moves away from dead center positioiiand permits the use of a scale with less congestion of graduations iiec'ting'or center `port-ion lll" also aids inde- @curved verticaillines of force at 'the/center.` l As the armature rotatesit movesintoa space Y y on the dial. The magneticflux aboutgthe con- 1 flectingthearniature.` The dialis''gradu'ated l in the vusual way to indicate the nposition of the need'lej38. j 'Y Mounting theilat armature 4to swing about an axis which liesin its own plane instead Aof perpendicular thereto vand providing acupsliaped conductor iiearly surrounding y'the arm ature p reduces an ammeter which is very wellfdaniped, this construction being'quite I claim: 'l 1. In an aminete'r, a

insensitive vto vibrationsfof the, inachine-` permanent magnet,an

to, and a'conduc'tor ladjacent the armature,

the surfaceof the conductor adjacent the 'armature beingfsu'bstantially concentric with the axis thereofQ" sideportions and a connectingportion, said sideportions being farther apart atv the center than at the edges, anarmature of inag- V2'. Inan amineter, a conductor comprising netic material pivotallyniounted Abetween said sideportions, and 'a permanent magnet mounted adjacent tlieretoin positionto hold said armature in line with the widestspa'ced y 'Y parts of the si 'demembers.

. 3. Inan ainineter, a conductor comprising parallel portions anda connectingportion,v

said parallel lpodr-tion'sfbeing closer together at theiredges thanattheir centers, an'arma- Y u ture ,ofmagnetic `sheet material mounted on a. fshaft parallel .with ,andi Obetween the side portions, and afpernianentrinagnet'mounted` adj acent said conductor...`

4. In anammeter, af conductorcoinprising Vtwo substantially concentric diametrically Y iio opposedcylindrical sections and a-connec-,

vtion therebetween, an'armature ofmagnetic` material pivotallyimounted ona shaft con# magnet-,adj acent said armature. v l 5.` In an ammeter, aconductor having' two spaced walls, a pointer' swinging` shaft pivf otally mounted betweensaid v vaf.ll's,anarma-` ture'inounted on said shaft, andme'ansto ,bias said armature andpointertoj .zero po-A- sition,

i 6. an ammeter, a casing,a pairofbifackpermanent Y.

ets secured in the casing, said brackets including spaced walls, a bridge piece connecting the walls, said brackets and bridge piece formin a conductor, a pointer swinging shaft pivotally mounted between said brackets, an armature mounted on said shaft, and

a magnet to bias said pointer to zero position. 7. The structure of claim 6, said magnet secured to said bridge member.

8. 'Ihe structure of claim 6, said brackets having flanged extensions to which said bridge piece is connected.

9. The structure of claim 6, and a finger on said bridge, said finger :extending under v an armature mounted on said shaft, and f means to bias said armature and pointer to Zero position.

12. In an ammeter, a conductor having spaced arcuate walls each forming a part of the saine cylindrical surface, a pointer swinging shaft pivotally mounted between said walls, an armature mounted on said shaft,V and means to bias said armature and pointerv to zero position. y Y

13. In an ammeter, a casing, a pair of brackets secured in the casing, said brackets including spaced walls, a bridge piece connecting the walls, said brackets and bridge piece forming a conductor, a pointer swinging shaft pivotally mounted between said brackets, an armature mounted on said shaft,

a magnet to bias said pointer to zero position, and integral lugs on lsaid bridge piece to retain said magnet.

14. In an ammeter, a casing, a pair of brackets secured in the casing, said brackets including spaced walls, a bridge piece connecting the walls, said brackets and bridge piece forming a conductor, `a pointer swinging shaft pivotally mounted between said brackets, an armature mounted on said shaft,

a magnet to bias said pointer tozero position,

' and .feet on said brackets by means of vwhich said brackets are secured to the casing. y In testimony whereof I aiiiX my signature.

JESSE E. ESHBAUGI-I. 

